The present invention relates to xcexc-oxo-bis-metallocene complex compounds and catalysts using same for the polymerization of olefins as well as polymerization processes. In particular, the present invention is featured by using as the metallocene complex compounds those having cyclopentadienyl rings, especially a bridged cyclopentadienyl ligand.
It is known that a variety of metallocene complex compounds are proposed as a component for the polymerization of olefins and that various olefin polymers can be produced by selecting the sort of metallocene complex compounds. Especially in the polymerization of propylene, it is publicly known that any of the atactic polypropylene, isotactic polypropylene and syndiotactic polypropylene can be produced. (Makromol. Chem., Rapid. Commun. 1983, 4,417-421; Angew. Chem., Int. Engl. 1985, 24, 507-508; J. Am. Chem. Soc. 1988, 110, 6255-6256; etc.) Purification of metallocene complex compounds is usually carried out by washing, extraction with a solvent, recrystallization and the like means. However, a considerable amount of metallocene complex compounds remain in a residue after purification, e.g. in washing liquids and a mother liquid of recrystallization, and the metallocene complex compounds cannot be recovered in some cases so that it incurs economical disadvantage.
Depending on the positions of substituents at the time of synthesis, metallocene complexes may permit the existence of stereoisomers. In the event a mixture of complex isomers formed on synthesis is straightforwardly used for polymerization of olefins where different olefin polymers are produced according to the different nature of the isomers, the resultant polymer will become a mixture of two different polymers. In case a uniform polymer is to be produced, therefore, the mixture of polymers has to be separated. For obtaining a highly pure isomeric form, however, repeating of the separation operations was necessary so that efficiency of the production was extremely low.
In Japanese Laid-open Patent Appln. No. Hei. 10-67793, there is disclosed that a method of changing the racemic/meso ratio wherein unnecessary isomer is decomposed with a decomposing agent such as acidic hydrogen atom or a reactive halogen atom. This method pertains to changing of the racemic/meso ratio by decomposing either one of the isomers, and more precisely, the racemic form is decomposed with ethylene-bis(4,7-dimethylindenyl)zirconium dichloride to obtain the pure meso form. As the other isomer is decomposed, however, this decomposed isomer cannot be used as catalyst component so that this method is regarded economically less interested.
A number of references are known concerning xcexc-oxo-bis-metallocene complex compounds having non-bridged cyclopentadienyl ligans, for example, Inorganic Chemistry 15, No. 9, 1976 disclosing that dimethylhafnocene is brought into contact with water in the air to form xcexc-oxo-bis(methylhafnocene) and Comprehensive Organometallic Chemistry 4, 1982, 527-528 disclosing a xcexc-oxo-complex compound containing a briged ligand.
In addition, Japanese laid-open Patent Appln. No. Hei. 7-233211 discloses a catalyst for the polymerization of olefins which contains a xcexc-oxo-complex combining metals of two nuclear complexes bridging Cp.
It is an object of the present invention to provide a novel xcexc-oxo-bis-metallocene complex compound excellent in crystallinity and separability and capable of being used as a catalyst component for the polymerization of olefins.
It is another object of the present invention to provide a catalyst for the polymerization of olefins which comprises the aforesaid novel xcexc-oxo-bis-metallocene complex compound.
It is still another object of the present invention to provide a process for polymerizing olefins by the aid of the above catalyst.
As a result of extensive research made to attain the aforesaid objects, it has now been found that xcexc-oxo-bis-metallocene complex compounds having an Mxe2x80x94Oxe2x80x94M bond are excellent in crystallinity and easily capable of being isolated from a reaction liquid at the time of synthesis and can be employed as a catalyst component for the polymerization of olefins. The present invention has been accomplished on the basis of the above finding.
According to the present invention, there is provided a xcexc-oxo-bis-metallocene complex compound represented by the formula (1): 
wherein M stands for a transition metal belonging to Group III, IV, V, VI, Lantanoid or Actinoid of the Periodic Table, n stands for an integer of 1 or 2, Y stands for carbon, silicon, germanium or tin, X""s may be the same or different and each independently stands for a halogen atom, a halogenoid atomic group, a hydrocarbon group having 1-20 carbon atoms which may contain a silicon, germanium, oxygen, sulfur, or nitrogen, or a monocyclic or polycyclic heteroaromatic group which may contain a hetero atom or atoms selected from the group consisting of oxygen atoms, sulfur atoms and nitrogen atoms in the 5-membered or 6-membered ring or rings thereof and which may be substituted on the ring or rings thereof by other substituents, R1, R2, R3, R4, R5, R6, R7, R8, R9 and R10 may be the same or different and each stands for hydrogen, an alkyl group having 1-20 carbon atoms, a cycloalkyl group having 3-20 carbon atoms, an alkenyl group with 2-20 carbon atoms, an aryl group having 6-20 carbon atoms, an alkylaryl group having 7-20 carbon atoms, or an aralkyl group having 7-20 carbon atoms with the proviso that these groups may contain a silicon, germanium, oxygen, sulfur, or- nitrogen, or a monocyclic or polycyclic heteroaromatic group which may contain a hetero atom or atoms selected from the group consisting of oxygen atoms, sulfur atoms and nitrogen atoms in the 5-membered or 6-membered ring or rings thereof and which may be substituted on the ring or rings by other substituents with the proviso that the adjacent substituents on the cyclopentadienyl groups may form together a cyclic structure having 5-8 carbon atoms and the cyclic structure may be an aromatic ring, that R9 and R10 may form together with Y a cyclic structure having 4-8 carbon atoms and which may contain oxygen, sulfur and nitrogen, and that R1-R8 are not hydrogen at the same time.
According to the present invention, there is also provided the aforesaid xcexc-oxo-bis-metallocene complex compound wherein R2, R3, R6 and R7 in the above formula (1) are not hydrogen at the same time.
According to the present invention, there is further provided the aforesaid xcexc-oxo-bis-metallocene complex compound wherein M and Y in the above formula (1) each stands for titanium, zirconium or hafnium and for carbon, silicon or germanium, respectively.
According to the present invention, there is still another provided a xcexc-oxo-bis-metallocene complex compound represented by the formula (2): 
wherein M stands for titanium, zirconium, or hafnium, n stands for an integer of 1 or 2, Y stands for carbon, silicon, or germanium, X""s may be the same or different and: each independently stands for a halogen atom, a halogenoid atomic group, a hydrocarbon group hang 1-20 carbon atoms which may contain silicon, germanium, oxygen, sulfur or nitrogen, or a monocyclic heteroaromatic group which may contain a hetero atom or atoms selected. from the group consisting of oxygen atoms, sulfur atoms and nitrogen atoms in the 5-membered or 6-membered ring or rings. thereof and which may be substituted on the ring or rings thereof by other substituents, R1, R2, R4, R5, R7 and R8 may be the same or different and each stands for hydrogen, an alkyl group having 1-20 carbon atoms, a cycloalkyl group having 3-20 carbon atoms, an alkenyl group with 2-20 carbon atoms, an aryl group having 6-20 carbon atoms, an alkylaryl group having 7-20 carbon atoms, or an aralkyl group having 7-20 carbon atoms with the proviso that these groups may contain silicon, germanium, oxygen, sulfur, or nitrogen, or a monocyclic or polycyclic heteroaromatic group which may contain a hetero atom or atoms selected from the group consisting of oxygen atoms, sulfur atoms and nitrogen atoms in the 5-membered or 6-membered ring or rings thereof and which may be substituted on the ring or rings by other substituents with the proviso that R1 and R2 may form together a cyclic structure having 5-8 carbon atoms and the cyclic structure may be an aromatic ring, that R7 and R8 may form a cyclic structure having 4-8 carbon atoms and which may contain oxygen, sulfur and nitrogen, and that R1, R2, R4, R5, R7 and R8 are not hydrogen at the same time.
According to the present invention, there is still further provided the aforesaid xcexc-oxo-bis-metallocene complex compound wherein R2 and R7 in the above formula (2) are substituents other than hydrogen in which ligands coordinated to the two M""s are commonly in meso position.
According to the present invention, there is still further provided a catalyst for the polymerization of olefins which comprises, as essential components thereof, at least one of the xcexc-oxo-bis-metallocene complex compound represented by the formula (1) (the component A) and at least one of the cocatalyst selected from the group consisting of (a) an aluminoxane, (b) an ionic compound and (c) a Lewis acid (the component B).
According to the present invention, there is still further provided the aforesaid catalyst for the polymerization of olefins wherein the component A is a xcexc-oxo-bis-metallocene complex compound represented by the formula (1) in which M is titanium, zirconium or hafnium, Y is carbon, silicon or germanium.
According to the present invention, there is still further provided the aforesaid catalyst for the polymerization of olefins wherein the component A is a xcexc-oxo-bis-metallocene complex compound represented by the. formula (2).
According to the present invention, there is still further provided the aforesaid catalyst for the polymerization of olefins wherein the component B is (a) an aluminoxane.
According to the present invention. there is yet further provided a process for the polymerization of olefins in the presence of the aforesaid catalyst for the polymerization of olefins.